74 MORPHOLOGY OF SPERMATOPHYTES 



regarded the ovuliferous scale in Abieteae as an open carpel, 

 which is lacking in Cupresseae. 



One of the simplest explanations of these problematical 

 structures was that proposed by Sachs 13 in 1868, and afterward 

 elaborated more fully by Eichler. 18 They contended that the 



FIG. 59. Abnormal strobili of Abies sp. : the staminate cone at lower right-hand corner 

 is almost normal ; all the others have microsporangia both above and. below, with 

 ovuliferous scales between. 



bract is a carpel and the ovuliferous scale a ligular outgrowth 

 from it, calling attention to a similar condition of things in the 

 leaves of Isoetes and Selaginella. Such a ligular placenta does 

 not appear in certain groups, as Cupresseae, Taxodieae, and Podo- 

 carpeae, and in these cases the bract is evidently an open carpel. 

 The simplicity of this explanation has commended it to writers 

 of text-books, and hence it is perhaps the view which is most 

 current. 



In 1869 Van Tieghem 14 presented his conclusions based 

 upon anatomical structure a new point of view. He claimed 

 that the ovuliferous scale is the first and only leaf of an axillary 

 branch, although he suggested the possibility of two fused leaves, 

 and bases his statement on the course and orientation of the 

 bundles. He states that the bundles of bract and ovuliferous 

 scale leave the main axis each in its own sheath, and thus repre- 

 sent independent systems of bundles ; that the uppermost 

 divides and forms an arc with inverted orientation, the arrange- 



